Fig. 6

FN-inhibitor blocks chemoresistance inducing effect of PSC-secreted FN on PCCs via downregulation of ERK1/2 phosphorylation. a PCCs seeded on 96-well plates with- or without FN-coating as indicated. Cell were incubated with SFM or PSC-CM for 24 h and/or RGDS (FN inhibitor; 20 μM) for 4 h prior to incubation with gemcitabine (10 μM) for 48 h. Cell viability was determined using the MTT assay. *p < 0.05, **p < 0.01 for control vs gemcitabine; #p < 0.05, ##p < 0.01 and $p < 0.05, $$p < 0.01 for SFM vs PSC-CM/FN/RGDS in control (black bars) and gemcitabine (white bars), respectively. b The table indicates gemcitabine-induced cytotoxicity in percentage, PSC-CM-induced resistance to gemcitabine, and resistance following subsequent incubation with RGDS. The resistance developed was calculated by relative reduction in cytotoxicity between SFM and PSC-CM or PSC-CM + RGDS. *p < 0.05, **p < 0.01 comparing SFM with PSC-CM or SFM vs PSC-CM + RGDS. c The cells were lysed and proteins subjected to immunoblotting using anti-pERK1/2 and anti-ERK1/2 antibodies. GAPDH was used as a loading control. Data are the mean ± SEM of triplicate determinations. FN, fibronectin; PCC, pancreatic cancer cell; PSC, pancreatic stellate cell; PSC-CM, PSC-conditioned medium; SFM, serum-free DMEM